In general, categorization of songs in the music space is limited to genres. For example, if a user wants to listen to rock or hip-hop, it can be relatively easy to find music in a specific genre. But in some cases a user may wish to define a different category of music, such as music appropriate for play while the user is at the gym, driving, or reading a book. Categories such as “gym music”, “reading music” and “driving music” may overlap with multiple genres, and songs in these categories can be difficult to tag on a song-by-song basis in an automatic way.